Apologies to all camels if this sullies your good character, but I liked the simile and had fun finding a photo of a camel who might be described as having a vindictive look.
‘… vindictive as a camel.’
Source: Nikos Kazantzakis, The Last Temptation, trans. P.A. Bien (London: Faber and Faber, 1983), p. 390
Photo credit: krystianwin at pixabay.com